Mesenchymal Stem Cell Response to Static Tension, Cyclic Tension, and Vibration Brooke McClarren, Ayesha Aijaz, Matthew Teryek, Ronke Olabisi

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1 Mesenchymal Stem Cell Response to Static Tension, Cyclic Tension, and Vibration Brooke McClarren, Ayesha Aijaz, Matthew Teryek, Ronke Olabisi Department of Biomedical Engineering, Rutgers University, New Brunswick, NJ

2 Multipotent and capable of becoming any mesenchymal tissue. Certain stimuli can cause cell commitment. Mechanical Chemical Electrical Thermal

3 Mechanical stimulation initiates differentiation down specific lineage Substrate rigidity Stress/Strain magnitude Stress/Strain duration Stress/Strain type: shear, tension, compression, Static vs cyclic

4 1. Chen et al. 2. Fang et al. 3. Van Eijk et al. 4. Zhang et al. 5. Jagodzinski et al. Mesenchymal Stem Cells (MSCs) in Tensile Strain Load Ref. Cell Scaffold Parameter Results 1 hmsc Collagen based 3% strain osteogenic 1 hmsc Collagen based 10% strain tenogenic Static 2 mmsc Poly(caprolactone) 10% strain tenogenic 3 gmsc Poly(lactic-co-glycolic acid) 6.7 N inhibition Static loading trends towards osteogenic lineages 4 hmsc Silicon, Gelatin 1% 10% strain tenogenic Cyclic 5 hmsc Silicon 8% strain tenogenic 5 hmsc Silicon 2% strain osteogenic Greater magnitude trends tenogenic. Lower magnitude trends to osteogenic.

5 MSCs in Compression, Shear, Vibration Load Ref. Cell Scaffold Parameter Results 6 hmsc Collagen Sponge 10% strain osteogenesis Compressive 6 hmsc Collagen Sponge 15% strain osteogenesis & chondrogenesis Investigated for chondrogenic differentiation. Small number result in osteogenesis 7 hmsc 2D construct 1.2 Pa osteogenesis Shear Stress 8 hmsc Ficoll Paque 9 dynes/cm 2 osteogenesis Trends towards osteogenesis. Few cases, inhibition of osteogenesis. Vibration 9 hmsc Microencapsulation 0.3 g osteogenic 6. Michalopoulos et al. 7. Delaine-Smith et al. 8. Yourek et al. 9. Mehta et al.

6 Scaffold Study Drawbacks Scaffolds were modified with biofactors Scaffolds were derived from natural sources Cells were seeded on scaffolds in 2D configurations Scaffolds adds biological input and confounds the mechanical stimuli. In order to isolate the mechanical stimuli, it is necessary to use a bioinert scaffold.

7 Polyethylene glycol diacrylate (PEGDA) Widely used in tissue engineering Highly hydrophilic Crosslinked synthetic polymer-based networks Tunable physical properties Bioinert Resists protein adsorption Low cell adhesion (eg: immune cells) Lacks biochemical or microarchitectural cues These combined properties enables the isolation of cell responses to mechanical stimulation within PEGDA scaffolds without confounding biochemical/microarchitectural cues imparted by natural polymers.

8 Cell Encapsulation Cell suspensions are combined with polymer precursors Cell-precursor solution is placed within a mold Mold is exposed to white light to polymerize solution into PEGDA hydrogel sheets Hydrogel precursor solution Cell suspension To mold To testing

9 Tensile Loading Hydrogel sheets were suspended within plastic films to retain media. Sheets within films were subjected to 24 hr: Static tension at 2 N Cyclic tension at 2 N, 10 Hz Vibration at 0.3 g, 3.0 g, 6.0 g Viability and differentiation were evaluated on Days 1, 4, 7, 14, and 21 Calcein AM, Ethidium Homodimer-1 (Live/Dead) Alkaline Phosphatase (Osteogenesis) Alizarin Red (Osteogenesis) Oil Red O (Adipogenesis)

10 Static tension Control hydrogel sheets with no stimulation Results: Viability Day 1 Day 4

11 6.0 g 3.0 g 0.3 g Control Day 1 Day 4 Day 7 Day 14 Day 21

12 Results: Viability Cell Viability from Day 1 to Day 21 of test samples with live (green) and dead (red) cells. The stained microspheres were then observed under an epifluorescent microscope. Higher cell viability with mild vibration Lowered cell viability with high vibration Static tension higher viability than control Overall viability decreases over later time points

13 Results: Alkaline Phosphatase (Day 4) Control Vibration 0.3 g Vibration 3.0 g Vibration 6.0 g

14 6.0 g 3.0 g 0.3 g Control Day 1 Day 4 Day 7 Day 14 Day 21

15 Results: Adipogenesis Oil Red O stains for test samples on Day 21 Vibration 3.0 g Vibration 6.0 g

16 Conclusions Mechanical stimuli of static tension, 0.3 g vibration, 3.0 g vibration improve viability of PEGDA hydrogel encapsulated cells. Vibrations of 6 g appear to cause aggregation of cells and reduce cell viability. Vibration of 0.3 g and 3 g highly promotes osteogenic differentiation. Vibration of 3.0 g promotes adipogenic differentiation.

17 Acknowledgements Members of the Olabisi Lab Kris White Corina White Sneha Mehta The first author was supported by the following: NASA Space Grant Consortium Academic Year Fellowship NASA Space Grant Consortium Summer Fellowship Rutgers Douglass Summer Stipend